diff --git a/composer.json b/composer.json
index adb13826..1f16c12e 100644
--- a/composer.json
+++ b/composer.json
@@ -11,6 +11,7 @@
     },
     "require": {
         "php": ">=7.2.0",
+        "guzzlehttp/streams": "^3.0",
         "guzzlehttp/guzzle": "^7.2"
     },
     "require-dev": {
diff --git a/src/aliases.php b/src/aliases.php
index caaa2041..ffd92f6b 100644
--- a/src/aliases.php
+++ b/src/aliases.php
@@ -15,10 +15,12 @@
  * limitations under the License.
  */
 /**
- * Alias.php creates aliases for the classes to match the 
+ * Alias.php creates aliases for the classes to match the
  * original names used in the php55 sdk. This is for the
- * convenience of migration to php7+ sdk. Alias.php is 
+ * convenience of migration to php7+ sdk. Alias.php is
  * included in the autoloader inside the composer.json.
  */
 
-@class_alias('Google\AppEngine\Api\AppIdentity\AppIdentityService', 'google\appengine\api\app_identity\AppIdentityService');
+if (!class_exists('google\appengine\api\app_identity\AppIdentityService')) {
+    @class_alias('Google\AppEngine\Api\AppIdentity\AppIdentityService', 'google\appengine\api\app_identity\AppIdentityService');
+}
\ No newline at end of file